you need to get your alk. in line before you start with your ph. BUT before you do any of that you need to make sure you have no phosphates, phosphates is the food algae eats and they make you have a cholrine level of zero. to get them out go to your pool store and get a bottel (2L) of phos FREE, use the proper amount wait 4 hours and start on the other things. another thing could be you may have a metal in your pool when you shock the pool it oxides the water well with a metal it will just oxide the metal which will cause it to rust, the color will be green. phospates or metals should be delt with 1st before going on to other steps, i work for leslies pools and we check for both phospates and metals for free just come on by with a sample.

The testing of phosphates and the sale of phosphate removers is the latest rage among pool stores. It is true that removing phosphates will remove a source of algae food (they don't remove nitrates, however) and will usually inhibit algae, but phosphate removers are expensive and phosphates can get reintroduced into your pool.

Even pools high in phosphates can usually keep away algae with chlorine alone, but most people don't maintain sufficient Free Chlorine (FC) levels relative to the Cyanuric Acid (CYA) levels and pool stores don't tell you about that (the manufacturers of Trichlor/Dichlor don't tell them about the chlorine/CYA relationship and such manufacturers deny that this affects "real pools", but they are wrong as proven by hundreds of pool users on multiple forums).

Basically, if you don't maintain an FC level that targets 11.5% of the CYA level and is always at least at a minimum of 7.5% of the CYA level at all times, then you risk getting algae. Shocking a pool requires maintaining an FC level of 40% of the CYA level to quickly remove algae, but if you the CYA is very high, then a partial drain/refill is needed to reduce the CYA and that should be done while using less chlorine (around 20% of the CYA level) to keep the algae in check.

See this post for how a pool filled with algae upon spring opening can be cleared with chlorine alone. This post and this post are further examples of how chlorine alone can kill algae. But if manufacturers of Trichlor and Dichlor and algaecides and phosphate removers told pool stores about this or how you can prevent the algae in the first place via chlorine alone, they wouldn't sell as much product.

You should also get yourself a good test kit, something else most pool stores don't have, namely the Taylor K-2006 (NOT the K-2005 some pool store's sell) which you can get from Taylor here or from Leslie's online here or the even better test kit based on the Taylor kit from tftestkits here. You need to maintain a shock level of chlorine until three things all occur: 1) the pool is crystal clear, 2) you measure minimal (< 1 ppm) drop in FC overnight, 3) you measure minimal (<= 0.5 ppm) Combined Chlorine (CC). Getting rid of the algae may require frequent brushing, cleaning of the filter, and in the worst case the use of a flocculant with vacuum to waste. This is why it is so much better to prevent algae in the first place.

After you have gotten rid of the algae, if you feel you are unable or unwilling to maintain the FC level at all times or want to use Trichlor pucks/tabs or Dichlor powder/granules even though they increase CYA levels, then you should use a weekly PolyQuat 60 algaecide (see this post) to keep away algae even when the chlorine drops too low relative to CYA.

You need to get your pH higher as the low pH can rust metal. You can lower your TA by following the procedure in this post.

One more thing, use only unscented bleach or chlorinating liquid to shock your pool with chlorine. These do not add any CYA to the water nor do they increase Calcium Hardness (CH). With Trichlor, for every 1 ppm FC it also adds 0.6 ppm CYA. With Dichlor, for every 1 ppm FC it also adds 0.9 ppm CYA. With Cal-Hypo, for every 1 ppm FC it also adds 0.7 ppm CH. Did the pool store tell you about that -- I didn't think so. It's not their fault, really...the manufacturers intentionally keep them in the dark and they just end up frustrating more and more pool users who flood the many pool forums that have cropped up. I'd like to work with Leslie's or other retailers to break this vicious cycle as the manufacturers do not want to work with me (I've asked).

NOTE: when adding chlorine to the pool, especially if it's a vinyl pool, do so very slowly over the water flow from the return in the deep end with the pump running. For extra safety, pre-mix the chlorine in a bucket of pool water and pour slowly into the pool and then use a brush to stir up the water near the bottom where you pour (especially if you don't have a floor drain as is the case with most above-ground pools).

Aeration works no question about it. Went back and forth with chemicals to no avail. As soon as turned bubbles on in jaccuzi saw near instant results. Added acid to get TA correct then bubbles to increase pH. Changed jacuzzi pH from 6.8 to 7.8 in 15 minutes. Used overflow and bubbles to do entire pool. Overflow by itself did not work for me, bubbles made all the difference. Thanks pool geek, you are the man.

Thanks for the compliment. I can't take credit for figuring out the aeration technique as I first heard about that at The Pool Forum, though I did work out the chemistry/physics behind it to determine the relative rates at various TA and pH. See this post where I refer to those sites that really should get the full credit for what we've learned. It's a group effort and I just play one part (mostly a highly technical one).